1. Field of the Invention
The present invention relates generally to wireless communication. More particularly, the present invention relates to improving interoperability of wireless devices employing different technology protocols or standards and working in close proximity to one another, or when embedded in a same enclosure.
2. Background of the Invention
The ISM (Industrial Scientific Medical) band includes 902-928 MHz, 2.4-2.483 GHz, and 5.725-5.875 GHz frequency ranges. In the United States, the ISM band is unlicensed, which means that any of the ISM band frequency ranges can be used in a variety of radio frequency (RF) applications as long as Federal (FCC) Communications Commission's part 15 rules are followed. One such RF application involves cordless telephones, which operate in each of the 900 MHz, 2.4 GHz, and 5.8 GHz ranges and typically employ a technology based on Worldwide Digital Cordless Telecommunications Standard (WDCT). Another application of the ISM band involves the Bluetooth (BT) wireless technology standard (also referred to hereinafter as “protocol”), which is deployed in the 2.4 GHz range frequencies and finds application in handheld devices, headsets, computers, and home appliances, among others. Both BT and WDCT employ frequency hopping spread spectrum (FHSS) technologies which provide for a signal to be carried over channels that can hop between different frequencies within an assigned frequency range.
Another prominent standard operating in the ISM band is the so called 802.11 standard employed frequently in wireless local area networks (LAN), computers, and related devices.
In a typical home, office, or industrial environment, a combination of devices employing two or all three of the above standards may be found. Such devices when operated in close proximity to one another, for instance, in the same room, will often interfere with one another during operation. For example, operation of a BT-based cell phone in close proximity to a WDCT 2.4 GHz cordless telephone would likely cause unacceptable interference for both Bluetooth and WDCT transceivers in the 2.4 GHz ISM band. In a situation in which a BT transceiver is located in a cordless handset, or an external Bluetooth module to support a cordless headset is in use with cordless handset that already has a conventional 2.4 GHz cordless telephone transceiver, significant interference can also be expected. Due to the significant interference, an acceptable communications session between a BT headset and the 2.4 GHz WDCT cordless handset may not be achievable.
The IEEE802.15.2 working group has published some proposed techniques for enhancing interoperability between devices employing 802.11 and BT standards. However, at the present time, there is no known technique for suppressing interference in an environment where devices employing the 802.11, WDCT, and BT standard are operating. This renders it extremely problematic for instance, to develop and deploy a communications product that can combine transceivers employing all three common standards. Additionally, as devices employing the above standards continue to proliferate, the use of multiple devices employing different standards will be increasingly used in close proximity to one another. For example, if a cordless phone employing WDCT standard were operated in proximity to a wireless internet router employing the 802.11 standard, and also close to a separate BT phone, significant interference among all three devices could be anticipated. FIG. 1 illustrates an example of the frequencies that could be employed during operation of the above-named devices. During a communication session, the BT and WDCT (FHSS) devices each occupy a series of channels, in which one channel (about 1 MHz in bandwidth) at a time is occupied. During an FHSS session, a signal transmission continually cycles between channels, such that many different channels are occupied within the space of a short time frame, as illustrated in FIG. 1. An 802.11 channel occupies about 22 MHz of bandwidth and is fixed during a given communications session. As is evident, there is potentially significant overlap (interference) of BT and WDCT channels with the 802.11 channel (also referred to hereinafter as “band”). In addition, the BT and WDCT channels occupy the same channel frequencies in several places in the 2.4 GHz band.
In light of the above discussion, it will be appreciated that a need exists for developing a system to provide for interoperability of RF communication devices in close proximity, in which interference is minimized.